In the conventional drilling of an oil and gas well, a number of drill pipes (each approximately 30 feet in length) are connected together, for example by threaded connections, to form the drill string used to drill the well bore. Each section of drill pipe is often referred to as a drill pipe joint. A borehole assembly (BHA), which includes the drill bit, is connected to the lower end of the drill string. The drill string is typically suspended from the derrick and rotated by a rotary table located on the floor of the drill rig.
As the drilling operation proceeds deeper into the earth, additional drill pipe joints must be connected to the existing string at the drilling rig floor and lowered into the borehole. Certain of the drill pipe joints may be fitted with collars or spacers or other accessories used, for example, to keep the drill string spaced from the well bore wall, or jars or sensors. For deeper wells, it may be necessary to connect hundreds of drill pipe joints together to drill the well bore to the desired depth, which may be many thousands of feet below the surface.
In addition, it is desirable to stabilize the well bore and to isolate the bore from the surrounding earth formation. This is done by cementing tubular casing in the well. Casing may be added in stages. For example, surface casing may be run into the well after drilling about 500-1,000 feet. Subsequently, intermediate casing, which has a smaller diameter than the surface casing, may be run into the well over the next several thousand feet. Finally, production casing having yet a smaller diameter may be run into the well to the depth and location of the production zone.
When casing is added, the drill string must first be removed, or tripped out of, the well. As the drill string is removed, the drill pipe joints must be disassembled from the drill string and stored temporarily for later use. If no further drilling is anticipated, the drill joints are disassembled and prepared for shipment off site. Casing is run into the well in segments (typically in lengths of about forty feet), connected end to end, for example, by threaded connections. The casing segments may be referred to as casing joints. The casing string is cemented in place by pumping cement at high pressure into the well where it is forced up the annulus between the outer surface of the casing and the side of the well bore. After surface or intermediate casing is cemented in place, the drill string is tripped back into the well to drill to a further depth using a drill bit having a smaller diameter than used previously. In this process, the drill pipe joints used previously are again connected one by one as the drill string is lowered into the well, and additional drill pipe joints are added as the hole is further drilled to a lower depth.
Drilling may proceed in a vertical or near vertical direction to a certain depth, for example as much as 7,000 to 10,000 feet. Thereafter, the direction of the well bore may deviate from vertical. Known techniques exist whereby a well bore can be turned, or dog legged, from an approximately vertical orientation to an approximately horizontal orientation. Thereafter, drilling may continue along a horizontal length of up to several thousand feet into the target production zone. Although each drill pipe joint is relatively rigid, the drill string collectively is flexible due to its large length relative to the diameter of the drill pipe joints.
Once the well has been drilled to the desired depth, including any horizontal offset, the well must be completed. The drill string must again be tripped out of the well and the drill pipe joints disassembled from one another. Next, the production string is run into the well. The production string is made up of segments of production tubing connected end to end, for example by threaded connections. The production tubing provides a conduit for the oil or gas to travel from the production zone to the surface.
As can be appreciated, the process of producing a well involves many steps during which the drilling, casing and completion operation must be interrupted to add joints to the string as the string is lowered into the well or remove joints as the string is lifted from the well. These operations are also interrupted when it is necessary to trip the drill string in its entirety out of the well. It is desirable to increase the efficiency of these operations in order to minimize the time necessary to drill, case and complete a well. Doing so diminishes costs for the drill operator and thus increases profit, and may determine the economic viability of a particular well project.
Drill pipe joints, casing joints and production tubing segments, sometimes referred to collectively herein as pipes, are typically stored horizontally on racks located near the drilling rig prior to being lifted to the drilling rig floor and deployed into the well. These pipes can weigh from several hundred to in excess of a thousand pounds and are typically handled with machinery. Typically, a gripping and hoisting device may be employed to transfer pipes from racks adjacent the drilling rig to a catwalk, and then to further transfer the pipes up a ramp to the drilling rig floor where they can be added to the drill string. Such a system is described, for example, in U.S. Pat. No. 6,976,540 to Berry. Other systems employ a power swivel, which engages the threads on the pipe before lifting it to the drilling rig floor. Still other systems employ elevators or clamps to lift a pipe to the drilling rig floor. Other systems have used pipe handling trailers to transfer pipe to the drilling rig floor, for example, U.S. Pat. No. 9,388,647.
Pipes are typically transported to the well site by truck and loaded and aligned onto the racks by forklift or crane. This process makes it challenging to keep track of the individual pipes and the number of pipes ready for deployment into the well in an automated or centralized fashion. It is also challenging to systematically or automatically control the order in which the pipes are added to the drill, casing or production string. In addition, the size and weight of the pipes makes them potentially dangerous to the personnel working on or near the drilling rig.
It is therefore desirable to improve the efficiency of the process of delivering pipes to a well site on the proper schedule and to track each individual pipe and tally the number of pipes ready for deployment into the well, and returned after removal from the well. It is further desirable to have an integrated system in which each pipe is pre-sorted into containers prior to arrival at the well site and transferred in an automated fashion from the containers to the drilling rig floor. Such an integrated system streamlines and organizes the process of delivering pipes to and removing pipes from the drilling rig floor, thereby increasing efficiency and ultimately the profitability of the drilling rig. It is also desirable to improve the safety of the workers around the pipes by having an integrated system that automates pipe handling functions.